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Christmas lights electricity calculator
Put your strands, watts a strand, hours a day, days and rate in: 12 strands at 40 watts a strand, 6 hours a day for 30 days at $0.16 a kWh cost $13.82 in all — 86.40 kWh, $0.46 a day, $1.15 a strand.
★ MONEY · WINTER · CHRISTMAS
Christmas Lights Electricity Cost: 12 Strands, $13.82
Put your strands, watts a strand, hours a day, days and rate in: 12 strands at 40 watts a strand, 6 hours a day for 30 days at $0.16 a kWh use 86.40 kWh and cost $13.82 in all — $0.46 a day, $1.15 a strand. This is the Christmas lights electricity cost tool: strands times watts times hours times days divided by 1000 is the electricity, and the electricity times your rate is the bill — a strand count tells you nothing until the wattage, the hours and the days are counted.
What does $13.82 mean?
It means 12 strands at 40 watts a strand, lit 6 hours a day for 30 days at $0.16 a kWh, draw 86.40 kWh and cost $13.82 in all, $0.46 a day and $1.15 a strand. The strands set the load, the wattage sets each strand, the hours stretch it daily, the days stretch it across the season, and the rate turns it into money: one more strand adds $1.15 at the defaults, while one more hour a day adds $2.30. The only judgement is the wattage itself and the rate itself — read the wattage off the strand label and the rate off the bill, since a guessed wattage or a supply-only rate settles the whole bill wrong.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Electricity | strands × watts × hours × days ÷ 1000 | 86.40 kWh — 12 × 40 × 6 × 30 ÷ 1000. |
| Cost | kWh × rate | $13.82 — 86.40 × $0.16. |
| Per day | cost ÷ days | $0.46 — $13.82 ÷ 30. |
| Per strand | cost ÷ strands | $1.15 — $13.82 ÷ 12. |
Three things to check before you trust the number
First, check the wattage against the strand label: 40 must be the watts actually printed for those strands, not a remembered figure for a different set — an LED strand and an old incandescent strand can differ tenfold, and the wrong wattage breaks the total by the full difference on every strand and every hour.
Second, check the hours against the timer: 6 must be the hours actually lit each day, not the hours the house is awake — a timer that runs dusk to midnight is not the same as lights left on all night, and an extra hour a day adds $2.30 over 30 days at the defaults.
Third, check the rate against the bill: $0.16 must be the all-in rate actually paid per kWh, not the supply-only figure before delivery charges and taxes — a tiered tariff can also push the display onto a dearer tier, so the rate on the last kilowatt-hour is the honest one.
Worked example
12 strands, 40 watts a strand, 6 hours a day, 30 days, $0.16 a kWh. Electricity: 12 × 40 × 6 × 30 ÷ 1000 = 86.40 kWh. Cost: 86.40 × $0.16 = $13.82. Per day: $13.82 ÷ 30 = $0.46. Per strand: $13.82 ÷ 12 = $1.15. In practice that means a month of evening lights costs about fourteen dollars all-in, and the 86.40 kWh figure is the one to set against the meter reading, since the kilowatt-hours stay the same whatever the tariff does.
Every branch, checked
At 6 strands, same watts a strand, hours a day, days and rate, Christmas lights electricity cost $6.91 in all (6 strands, 40 watts a strand, 6 hours a day, 30 days, $0.16 a kWh, 43.20 kWh, $0.23 a day, $1.15 a strand). At 8 hours a day, same strands, watts a strand, days and rate, Christmas lights electricity cost $18.43 in all (12 strands, 40 watts a strand, 8 hours a day, 30 days, $0.16 a kWh, 115.20 kWh, $0.61 a day, $1.54 a strand). At 40 days, same strands, watts a strand, hours a day and rate, Christmas lights electricity cost $18.43 in all (12 strands, 40 watts a strand, 6 hours a day, 40 days, $0.16 a kWh, 115.20 kWh, $0.46 a day, $1.54 a strand). At $0.20 a kWh, same strands, watts a strand, hours a day and days, Christmas lights electricity cost $17.28 in all (12 strands, 40 watts a strand, 6 hours a day, 30 days, $0.20 a kWh, 86.40 kWh, $0.58 a day, $1.44 a strand).
The reverses, worked backwards
Strands behind 12 strands — at the lower neighbor the figures are Christmas lights electricity cost $6.91 in all (6 strands, 40 watts a strand, 6 hours a day, 30 days, $0.16 a kWh, 43.20 kWh, $0.23 a day, $1.15 a strand). at the upper neighbor the figures are Christmas lights electricity cost $20.74 in all (18 strands, 40 watts a strand, 6 hours a day, 30 days, $0.16 a kWh, 129.60 kWh, $0.69 a day, $1.15 a strand). Days behind 30 days — at the lower neighbor the figures are Christmas lights electricity cost $9.22 in all (12 strands, 40 watts a strand, 6 hours a day, 20 days, $0.16 a kWh, 57.60 kWh, $0.46 a day, $0.77 a strand). at the upper neighbor the figures are Christmas lights electricity cost $18.43 in all (12 strands, 40 watts a strand, 6 hours a day, 40 days, $0.16 a kWh, 115.20 kWh, $0.46 a day, $1.54 a strand).
What the defaults assume
The defaults assume 12 strands, 40 watts a strand, 6 hours a day, 30 days and $0.16 a kWh, for one display on one meter. They do not assume the purchase price of the strands, a timer, or a second display — so treat $13.82 as the electricity cost for 12 strands at 40 watts a strand for 6 hours a day over 30 days, and check it against the bill actually received before budgeting it as exact.
Who uses this
- A homeowner budgeting December:: the $13.82 is the figure to set against the January bill.
- A renter splitting a shared display:: the per-strand figure is what each flat fairly owes.
- A decorator quoting a client display:: the kilowatt-hour figure is what each design fairly costs to run.
- A neighbour sizing a bigger display:: the per-strand figure shows what each extra strand really adds.
Accuracy & limitations
The arithmetic is exact for the inputs entered; the judgement is the wattage actually printed on the strands, the hours actually lit, the days actually lit, and the rate actually paid. Real bills vary with tiered tariffs, delivery charges and taxes, and timer drift — so treat $13.82 as the electricity cost for 12 strands at 40 watts a strand for 6 hours a day over 30 days at $0.16 a kWh, and check it against the bill actually received before budgeting it as exact.
Cite this calculator
Bright Side Kit, “Christmas Lights Electricity Cost: 12 Strands, $13.82”, https://brightoolbox.com/christmas-lights-electricity-cost-calculator/, accessed 3 November 2026. Students and researchers: cite the calculator name, the page URL and the date you used it, and quote the defaults (12 strands, 40 watts a strand, 6 hours a day, 30 days, 0.16 rate) so the result can be checked.
Frequently asked questions
How much does it cost to run Christmas lights for a month?
$13.82 on the defaults: 12 strands at 40 watts a strand, 6 hours a day for 30 days at $0.16 a kWh.
How many kilowatt-hours do 12 strands use?
86.40 kWh: 12 × 40 × 6 × 30 ÷ 1000.
What if I run the lights 8 hours a day?
$18.43: the same 12 strands for 8 hours a day over 30 days use 115.20 kWh.
Do LED strands cost less to run?
Only through wattage: at 5 watts a strand the same 12 strands for 6 hours a day over 30 days use 10.80 kWh and cost $1.73 — the strand count matters far less than the watts printed on the label.
How do I cut my Christmas lights electricity cost?
Use fewer strands or fewer hours: 6 strands cost $6.91 for the same 30 days, and a timer that keeps the display to 6 hours a day beats lights left on all night.
Is the rate on my bill the right rate to use?
Use the all-in rate per kWh, including delivery charges and taxes, and on a tiered tariff use the rate on the last kilowatt-hour — the supply-only figure understates the bill.